# coding: utf-8 from __future__ import absolute_import, unicode_literals from collections import OrderedDict from itertools import islice from django.utils import six from django.utils.safestring import SafeData from django_tables2.templatetags.django_tables2 import title from django_tables2.utils import Accessor, AttributeDict, OrderBy, OrderByTuple, call_with_appropriate, computed_values class Library(object): ''' A collection of columns. ''' def __init__(self): self.columns = [] def register(self, column): self.columns.append(column) return column def column_for_field(self, field): ''' Return a column object suitable for model field. Returns: `.Column` object or `None` ''' if field is None: return self.columns[0]() # iterate in reverse order as columns are registered in order # of least to most specialised (i.e. Column is registered # first). This also allows user-registered columns to be # favoured. for candidate in reversed(self.columns): if not hasattr(candidate, 'from_field'): continue column = candidate.from_field(field) if column is None: continue return column # The library is a mechanism for announcing what columns are available. Its # current use is to allow the table metaclass to ask columns if they're a # suitable match for a model field, and if so to return an approach instance. library = Library() @library.register class Column(object): ''' Represents a single column of a table. `.Column` objects control the way a column (including the cells that fall within it) are rendered. Arguments: attrs (dict): HTML attributes for elements that make up the column. This API is extended by subclasses to allow arbitrary HTML attributes to be added to the output. By default `.Column` supports: - *th* -- ``table/thead/tr/th`` elements - *td* -- ``table/tbody/tr/td`` elements - *cell* -- fallback if *th* or *td* isn't defined accessor (str or `~.Accessor`): An accessor that describes how to extract values for this column from the :term:`table data`. default (str or callable): The default value for the column. This can be a value or a callable object [1]_. If an object in the data provides `None` for a column, the default will be used instead. The default value may affect ordering, depending on the type of data the table is using. The only case where ordering is not affected is when a `.QuerySet` is used as the table data (since sorting is performed by the database). empty_values (iterable): list of values considered as a missing value, for which the column will render the default value. Defaults to `(None, '')` exclude_from_export (bool): If `True`, this column will not be added to the data iterator returned from as_values(). footer (str, callable): Defines the footer of this column. If a callable is passed, it can take optional keyword argumetns `column`, `bound_column` and `table`. order_by (str, tuple or `.Accessor`): Allows one or more accessors to be used for ordering rather than *accessor*. orderable (bool): If `False`, this column will not be allowed to influence row ordering/sorting. verbose_name (str): A human readable version of the column name. visible (bool): If `True`, this column will be rendered. localize: If the cells in this column will be localized by the `localize` filter: - If `True`, force localization - If `False`, values are not localized - If `None` (default), localization depends on the ``USE_L10N`` setting. .. [1] The provided callable object must not expect to receive any arguments. ''' # Tracks each time a Column instance is created. Used to retain order. creation_counter = 0 empty_values = (None, '') # Explicit is set to True if the column is defined as an attribute of a # class, used to give explicit columns precedence. _explicit = False def __init__(self, verbose_name=None, accessor=None, default=None, visible=True, orderable=None, attrs=None, order_by=None, empty_values=None, localize=None, footer=None, exclude_from_export=False): if not (accessor is None or isinstance(accessor, six.string_types) or callable(accessor)): raise TypeError('accessor must be a string or callable, not %s' % type(accessor).__name__) if callable(accessor) and default is not None: raise TypeError('accessor must be string when default is used, not callable') self.accessor = Accessor(accessor) if accessor else None self._default = default self.verbose_name = verbose_name self.visible = visible self.orderable = orderable self.attrs = attrs or getattr(self, 'attrs', {}) # massage order_by into an OrderByTuple or None order_by = (order_by, ) if isinstance(order_by, six.string_types) else order_by self.order_by = OrderByTuple(order_by) if order_by is not None else None if empty_values is not None: self.empty_values = empty_values self.localize = localize self.creation_counter = Column.creation_counter Column.creation_counter += 1 self._footer = footer self.exclude_from_export = exclude_from_export @property def default(self): # handle callables return self._default() if callable(self._default) else self._default @property def header(self): ''' The value used for the column heading (e.g. inside the ```` tag). By default this returns `~.Column.verbose_name`. :returns: `unicode` or `None` .. note:: This property typically isn't accessed directly when a table is rendered. Instead, `.BoundColumn.header` is accessed which in turn accesses this property. This allows the header to fallback to the column name (it's only available on a `.BoundColumn` object hence accessing that first) when this property doesn't return something useful. ''' return self.verbose_name def footer(self, bound_column, table): ''' Returns the content of the footer, if specified. ''' footer_kwargs = { 'column': self, 'bound_column': bound_column, 'table': table } if self._footer is not None: if callable(self._footer): return call_with_appropriate(self._footer, footer_kwargs) else: return self._footer if hasattr(self, 'render_footer'): return call_with_appropriate(self.render_footer, footer_kwargs) return '' def render(self, value): ''' Returns the content for a specific cell. This method can be overridden by :ref:`table.render_FOO` methods on the table or by subclassing `.Column`. If the value for this cell is in `.empty_values`, this method is skipped and an appropriate default value is rendered instead. Subclasses should set `.empty_values` to ``()`` if they want to handle all values in `.render`. ''' return value def value(self, **kwargs): ''' Returns the content for a specific cell similarly to `.render` however without any html content. This can be used to get the data in the formatted as it is presented but in a form that could be added to a csv file. The default implementation just calls the `render` function but any subclasses where `render` returns html content should override this method. See `LinkColumn` for an example. ''' value = call_with_appropriate(self.render, kwargs) return value def order(self, queryset, is_descending): ''' Returns the queryset of the table. This method can be overridden by :ref:`table.order_FOO` methods on the table or by subclassing `.Column`; but only overrides if second element in return tuple is True. returns: Tuple (queryset, boolean) ''' return (queryset, False) @classmethod def from_field(cls, field): ''' Return a specialised column for the model field or `None`. Arguments: field (Model Field instance): the field that needs a suitable column Returns: `.Column` object or `None` If the column isn't specialised for the given model field, it should return `None`. This gives other columns the opportunity to do better. If the column is specialised, it should return an instance of itself that's configured appropriately for the field. ''' # Since this method is inherited by every subclass, only provide a # column if this class was asked directly. if cls is Column: if hasattr(field, 'get_related_field'): verbose_name = field.get_related_field().verbose_name else: verbose_name = getattr(field, 'verbose_name', field.name) return cls(verbose_name=title(verbose_name)) @six.python_2_unicode_compatible class BoundColumn(object): ''' A *run-time* version of `.Column`. The difference between `.BoundColumn` and `.Column`, is that `.BoundColumn` objects include the relationship between a `.Column` and a `.Table`. In practice, this means that a `.BoundColumn` knows the *"variable name"* given to the `.Column` when it was declared on the `.Table`. arguments: table (`~.Table`): The table in which this column exists column (`~.Column`): The type of column name (str): The variable name of the column used when defining the `.Table`. In this example the name is ``age``:: class SimpleTable(tables.Table): age = tables.Column() ''' def __init__(self, table, column, name): self._table = table self.column = column self.name = name self.current_value = None def __str__(self): return six.text_type(self.header) @property def accessor(self): ''' Returns the string used to access data for this column out of the data source. ''' return self.column.accessor or Accessor(self.name) @property def attrs(self): ''' Proxy to `.Column.attrs` but injects some values of our own. A ``th``, ``td`` and ``tf`` are guaranteed to be defined (irrespective of what's actually defined in the column attrs. This makes writing templates easier. ``tf`` is not actually a HTML tag, but this key name will be used for attributes for column's footer, if the column has one. ''' # prepare kwargs for computed_values() kwargs = { 'table': self._table, 'bound_column': self, } # BoundRow.items() sets current_record and current_value when iterating over # the records in a table. if getattr(self, 'current_record', False) and getattr(self, 'current_value', False): kwargs.update({ 'record': self.current_record, 'value': self.current_value }) # Start with table's attrs; Only 'th' and 'td' attributes will be used attrs = dict(self._table.attrs) # Update attrs to prefer column's attrs rather than table's attrs.update(dict(self.column.attrs)) # we take the value for 'cell' as the basis for both the th and td attrs cell_attrs = attrs.get('cell', {}) # override with attrs defined specifically for th and td respectively. attrs['th'] = computed_values(attrs.get('th', cell_attrs), kwargs=kwargs) attrs['td'] = computed_values(attrs.get('td', cell_attrs), kwargs=kwargs) attrs['tf'] = computed_values(attrs.get('tf', cell_attrs), kwargs=kwargs) # wrap in AttributeDict attrs['th'] = AttributeDict(attrs['th']) attrs['td'] = AttributeDict(attrs['td']) attrs['tf'] = AttributeDict(attrs['tf']) # Override/add classes attrs['th']['class'] = self.get_th_class(attrs['th']) attrs['td']['class'] = self.get_td_class(attrs['td']) attrs['tf']['class'] = self.get_td_class(attrs['tf']) return attrs def _get_cell_class(self, attrs): ''' return a set of the classes from the class key in ``attrs``, augmented with the column name (or anything else added by Table.get_column_class_names()). ''' classes = attrs.get('class', None) classes = set() if classes is None else {c for c in classes.split(' ') if c} return self._table.get_column_class_names(classes, self) def get_td_class(self, td_attrs): ''' Returns the HTML class attribute for a data cell in this column ''' return ' '.join(sorted(self._get_cell_class(td_attrs))) def get_th_class(self, th_attrs): ''' Returns the HTML class attribute for a header cell in this column ''' classes = self._get_cell_class(th_attrs) # add classes for ordering ordering_class = th_attrs.get('_ordering', {}) if self.orderable: classes.add(ordering_class.get('orderable', 'orderable')) if self.is_ordered: classes.add(ordering_class.get('descending', 'desc') if self.order_by_alias.is_descending else ordering_class.get('ascending', 'asc')) return ' '.join(sorted(classes)) @property def default(self): ''' Returns the default value for this column. ''' value = self.column.default if value is None: value = self._table.default return value @property def header(self): ''' The value that should be used in the header cell for this column. ''' # favour Column.header column_header = self.column.header if column_header: return column_header # fall back to automatic best guess return self.verbose_name @property def footer(self): return call_with_appropriate(self.column.footer, { 'bound_column': self, 'table': self._table }) def has_footer(self): return self.column._footer is not None or hasattr(self.column, 'render_footer') @property def order_by(self): ''' Returns an `.OrderByTuple` of appropriately prefixed data source keys used to sort this column. See `.order_by_alias` for details. ''' if self.column.order_by is not None: order_by = self.column.order_by else: # default to using column accessor as data source sort key order_by = OrderByTuple((self.accessor, )) return order_by.opposite if self.order_by_alias.is_descending else order_by @property def order_by_alias(self): ''' Returns an `OrderBy` describing the current state of ordering for this column. The following attempts to explain the difference between `order_by` and `.order_by_alias`. `.order_by_alias` returns and `.OrderBy` instance that's based on the *name* of the column, rather than the keys used to order the table data. Understanding the difference is essential. Having an alias *and* a keys version is necessary because an N-tuple (of data source keys) can be used by the column to order the data, and it's ambiguous when mapping from N-tuple to column (since multiple columns could use the same N-tuple). The solution is to use order by *aliases* (which are really just prefixed column names) that describe the ordering *state* of the column, rather than the specific keys in the data source should be ordered. e.g.:: >>> class SimpleTable(tables.Table): ... name = tables.Column(order_by=('firstname', 'last_name')) ... >>> table = SimpleTable([], order_by=('-name', )) >>> table.columns['name'].order_by_alias '-name' >>> table.columns['name'].order_by ('-first_name', '-last_name') The `OrderBy` returned has been patched to include an extra attribute ``next``, which returns a version of the alias that would be transitioned to if the user toggles sorting on this column, e.g.:: not sorted -> ascending ascending -> descending descending -> ascending This is useful otherwise in templates you'd need something like:: {% if column.is_ordered %} {% querystring table.prefixed_order_by_field=column.order_by_alias.opposite %} {% else %} {% querystring table.prefixed_order_by_field=column.order_by_alias %} {% endif %} ''' order_by = OrderBy((self._table.order_by or {}).get(self.name, self.name)) order_by.next = order_by.opposite if self.is_ordered else order_by return order_by @property def is_ordered(self): return self.name in (self._table.order_by or ()) @property def orderable(self): ''' Return a `bool` depending on whether this column supports ordering. ''' if self.column.orderable is not None: return self.column.orderable return self._table.orderable @property def verbose_name(self): ''' Return the verbose name for this column. In order of preference, this will return: 1) The column's explicitly defined `verbose_name` 2) The titlised model's `verbose_name` (if applicable) 3) Fallback to the titlised column name. Any `verbose_name` that was not passed explicitly in the column definition is returned titlised in keeping with the Django convention of `verbose_name` being defined in lowercase and uppercased/titlised as needed by the application. If the table is using queryset data, then use the corresponding model field's `~.db.Field.verbose_name`. If it's traversing a relationship, then get the last field in the accessor (i.e. stop when the relationship turns from ORM relationships to object attributes [e.g. person.upper should stop at person]). ''' # Favor an explicit defined verbose_name if self.column.verbose_name is not None: return self.column.verbose_name # This is our reasonable fallback, should the next section not result # in anything useful. name = self.name.replace('_', ' ') # Try to use a model field's verbose_name model = self._table.data.get_model() if model: field = Accessor(self.accessor).get_field(model) if field: if hasattr(field, 'field'): name = field.field.verbose_name else: name = getattr(field, 'verbose_name', field.name) # If verbose_name was mark_safe()'d, return intact to keep safety if isinstance(name, SafeData): return name return title(name) @property def visible(self): ''' Returns a `bool` depending on whether this column is visible. ''' return self.column.visible @property def localize(self): ''' Returns `True`, `False` or `None` as described in ``Column.localize`` ''' return self.column.localize class BoundColumns(object): ''' Container for spawning `.BoundColumn` objects. This is bound to a table and provides its `.Table.columns` property. It provides access to those columns in different ways (iterator, item-based, filtered and unfiltered etc), stuff that would not be possible with a simple iterator in the table class. A `BoundColumns` object is a container for holding `BoundColumn` objects. It provides methods that make accessing columns easier than if they were stored in a `list` or `dict`. `Columns` has a similar API to a `dict` (it actually uses a `~collections.OrderedDict` interally). At the moment you'll only come across this class when you access a `.Table.columns` property. Arguments: table (`.Table`): the table containing the columns ''' def __init__(self, table, base_columns): self._table = table self.columns = OrderedDict() for name, column in six.iteritems(base_columns): self.columns[name] = bc = BoundColumn(table, column, name) bc.render = getattr(table, 'render_' + name, column.render) # How the value is defined: 1. value_ 2. render_ 3. column.value. bc.value = getattr(table, 'value_' + name, getattr(table, 'render_' + name, column.value)) bc.order = getattr(table, 'order_' + name, column.order) def iternames(self): return (name for name, column in self.iteritems()) def names(self): return list(self.iternames()) def iterall(self): ''' Return an iterator that exposes all `.BoundColumn` objects, regardless of visiblity or sortability. ''' return (column for name, column in self.iteritems()) def all(self): return list(self.iterall()) def iteritems(self): ''' Return an iterator of ``(name, column)`` pairs (where ``column`` is a `BoundColumn`). This method is the mechanism for retrieving columns that takes into consideration all of the ordering and filtering modifiers that a table supports (e.g. `~Table.Meta.exclude` and `~Table.Meta.sequence`). ''' for name in self._table.sequence: if name not in self._table.exclude: yield (name, self.columns[name]) def items(self): return list(self.iteritems()) def iterorderable(self): ''' Same as `BoundColumns.all` but only returns orderable columns. This is useful in templates, where iterating over the full set and checking ``{% if column.ordarable %}`` can be problematic in conjunction with e.g. ``{{ forloop.last }}`` (the last column might not be the actual last that is rendered). ''' return (x for x in self.iterall() if x.orderable) def orderable(self): return list(self.iterorderable()) def itervisible(self): ''' Same as `.iterorderable` but only returns visible `.BoundColumn` objects. This is geared towards table rendering. ''' return (x for x in self.iterall() if x.visible) def visible(self): return list(self.itervisible()) def hide(self, name): ''' Hide a column. Arguments: name(str): name of the column ''' self.columns[name].column.visible = False def show(self, name): ''' Show a column otherwise hidden. Arguments: name(str): name of the column ''' self.columns[name].column.visible = True def __iter__(self): ''' Convenience API, alias of `.itervisible`. ''' return self.itervisible() def __contains__(self, item): ''' Check if a column is contained within a `BoundColumns` object. *item* can either be a `~.BoundColumn` object, or the name of a column. ''' if isinstance(item, six.string_types): return item in self.iternames() else: # let's assume we were given a column return item in self.iterall() def __len__(self): ''' Return how many `~.BoundColumn` objects are contained (and visible). ''' return len(self.visible()) def __getitem__(self, index): ''' Retrieve a specific `~.BoundColumn` object. *index* can either be 0-indexed or the name of a column .. code-block:: python columns['speed'] # returns a bound column with name 'speed' columns[0] # returns the first column ''' if isinstance(index, int): try: return next(islice(self.iterall(), index, index + 1)) except StopIteration: raise IndexError elif isinstance(index, six.string_types): for column in self.iterall(): if column.name == index: return column raise KeyError("Column with name '%s' does not exist; " "choices are: %s" % (index, self.names())) else: raise TypeError('Column indices must be integers or str, not %s' % type(index).__name__)